Copper-base alloys containing vanadium



, Pa ses oc 3,1936 I 2,059,560

UNITED STATES PATENT OFFICE Michael George Corson, New York, N. Y., assignor to Union Carbide and Carbon Research Laboratories, Inc., a corporation of New York No Drawing. Application March 17, 1936,

- Serial No. 69,364

2 Claims. (01. 75-154) The present invention relat s to the pp effective amounts of one or both of the elements b a l y n i app i o ta ns l chromium and vanadium and the further addilnatter in common wi h my ap icat n. Serial tion of substantial amounts of iron or cobalt. If No. 696,918 filed November 6, 1933. desired, the chromium or vanadium, or both, may

C pp -t n all ys. s tim s n a nin oth r he added in the form of ferro alloys; for instance, 5 elements such as phosph in m n n a commercial low. carbon ferrochromium conand nickel, are well-known to the art and are taming ab ut 50% to 95% chromium, or a low formed into various shape y asting and by carbon ferrovanadium containing about 30% to various known processes for working metals in 90% vanadium, or a ferro alloy containing both l 0-'the cold state. However, it has heretofore been vanadiu and hromiu l0 difllcult to hot work tin bronzes containing above When both iron and chromium or vanadium about 3% tin. For instance, in order to form are added, the iron crystallizes chiefly with the wire .or sheets from the so-called phosphor chromium or vanadium so thata tin bronze conbronze, it has been necessary first to heat the taining say 2% of 50% Ierrochromium appears,

cast ingot to a high temperature of not less than under the microscope, more like an alloy con- 15 100 C., hold it at this high temperature for many taming 1.75% to 2% chromium than like one h urs for th p pose of h m enizin the in ot containing 1% of chromium as would have been by diffusion, break the inset down 001d, anneal the case had the iron gone into solid solution in it, roll it down cold to a certain extent, again the alpha tin bronze.

anneal it, and to repeat the alternate cold work- Tin bronzes made according to the present 8' and a ng steps until the metal has atinvention and containing 3% to 10% tin, 0.5% taln d the d s d size nd sha At n stage to 2% chromium or 0.2% to 1% vanadium and h ho W r n en used, because the metal up to about 2% iron may be taken from the ingot cannot Wi stand the app n of a forging mold as soon as they are sumciently cold to hanhammer orhot rolls without cracking and break- 119, r h ated to 700 to 800 0., forged to about ing to pieces. one-half of the area of the original cross-section,

f I have discovered that copper-tin alloys can and finished into the desired shape by hot rolling. be made forgeable and rollable at elevated tem- Vanadium is somewhat diflicult to introduce p a llr y introducing in o h alloys c ain and in addition quite expensive, for which reaadditional l m nts whi h ar y sli htly solusons the use of an amount exceeding that which an hle i the Crystals of Solid pp and s n is necessary for the development of the capacity alpha in ronze, and which in addition have a for hot work (about 1%) is not usually desirable. much h er me ti poi t t an the bronze- The situation in the case of chromium is differ- Such additional elements are the first constituut: it can be introduced into molten bronze en to ry a u f the m lt n m s n easily enough, and its excess above the really cooling and thus effect favorable distribution of necessary amount of 1.5% does not seriously af- 'y nuclei. and influence the atoms pp fect hot workability but develops interesting and and tin o crystallize i a m constant p pe industrially desirable antifriction characteristics. ti n than is the case w normal n ry n It is well known, forinstance, that the usual 40 bronzes and with ternary tin bronzes in which bearing bronzes, working without a lining of a the d element forms a component the a p a low melting antifrlctlon alloy and containing tin solid solution. in amounts sufliclent to produce as a second con- Sultable additional elements are chromium and stituent the delta eutectoid or bronzite, do not vanadium and, to a lesser degree, iron and cobalt. work well if the bearing happens to become over- Vanadium is the most eflective of these elements heated. In fact, the bearings of hot rolling mills but it is difllcult and expensive to introduce into as used in steel making cannot be made at all of molten copper or molten bronzes. For this reasuch duplex (alpha plus delta) bronzes. The son chromium is preferred, this element being latter fail rapidly when their temperature apeil'ectlve as soon as about 0.5% is added. If iron proaches 500 C.

. or cobalt alone were to be used, at least 4%would To cope with this handicap special bronzes m be necessary to produce the desired effect of have been introduced containing less than 8% tin improving the hot workability of the bronze. and thereforecontalning no delta phase. In place According to the present invention, hot workof the delta phase a hard constituent, quite stable ability is imparted to copper-tin alloys containing at high temperatures, is introduced into the strucabout 3% to about 10% tin by the addition of ture of such bronzes by adding up to 0.3% of phosphorus and up to 3% nickel, the latter producing to some extent at least, flne' grains of nickel phosphide of the supposed formula NlaP.

I have found, however, that by increasing the amount of chromium added to the copper-tin base bronze, the phosphide can be replaced by a far larger and far more eflicient amount of chromium which crystallizes in the shape of irregular single crystals or their star-like aggregates. While the actual hardness of these chromium crystals is not well known, it can be safely assumed to be in the neighborhood of 200 Brinell, while the hardness of nickel-phosphide, a definite intermetallic compound, must be considerably higher. Therefore, the probability of scratching the journals of the rolling mill is far less in the case of a chromium containing bronze.

The amount of chromium present in such a tin br nze may be as high as 10%, but not more than 4 or 5% is desirable. Likewise, the amount of iron or cobalt may be as high as 10%.

The method of making such chromium or vanadium containing bronzes may vary to a great extent, as to raw materials, type of furnace, ma-

terial of the crucible, etc. The only essential thing is that the metal should be properly deoxidized before the introduction of the chromium and protected from further oxidation by a layer of a liquid flux. For the latter I prefer a mixture of fluorides of sodium and calcium, to which other fluorides may be added. I may employ a flux of commercially pure fused boric acid and borax and its mixtures with glass also may be used, but with less convenience.

To fllustrate a way of preparing such alloys, I shall state the following:

I take commercial bronze ingots and melt them in the usual graphite-clay crucibles. I add to them enough copper to bring the content of tin down to the desired level. I cover the molten alloy with a layer of fluorides about one-eighth inch in thickness in the molten state. I add just enough phosphor copper to make the melt quite fluid, usually not more than 0.05% phosphorus. Then I add chromium metal or ferrochrome or ferrovanadium or ferrochromewanadium in pieces large enough to be produced conveniently and without much expense and small enough to allow them to be fully covered by the liquid fluoride in those parts which protrude above the level of the molten bronze due to the difference in the specific weights. I

Next, I raise the temperature in the metal either by feeding more fuel and 'air to the furnace, or increasing its current input until it comes to about 1250 C. At this point chromium dissolves rapidly as does ferrovanadium. From time to time the pieces of the metal or of the ferro-alloy are pushed down under the surface of the molten bronze and the latter stirred to check the supersaturation of the top-layers with dissolved chromium or vanadium.

The liquid flux is next removed, by adding dry sand to it. In this manner a pasty mass of fluoride soaked sand forms, and it can be easily kept from flowing down into the'mold.

The final casting proceeds as usual, whether it is the manufacture of sand castings, ingots for forging, or castings in permanent molds. In the latter case about 0.2% aluminum may be added to inhibit the welding of the molten metal to the metal of the permanent mold.

It is to be understood that the copper-base alloys of the present invention may contain, in addition to tin and one or more of the elements chromium, vanadium, and iron in proportions within the limits specified herein, one or more of the elements, nickel, manganese, and aluminum in proportions up to say 10%. These elements do not contribute to the workability of the alloy in the hot state, but may be added for their known improvement effects in other respects. Small amounts of the usual deoxidizers, such as phosphorus, magnesium, and the like may also be present..

I claim:

1. A hot workable copper-base alloy containing about 3% to 10% tin, about 0.2% to 10% vanadium which imparts hot workability to the alloy, and the remainder substantially all copper.

2. A hot workable alloy containing about 5% to 10% tin, about 0.2% to 1% vanadium, and the remainder substantially all copper.

- MICHAEL GEORGE CORBON. 

